Instrumentation and surgical method for image-guided microendoscopic decompression

ABSTRACT

Instrumentation for microendoscopic surgery comprises a retractor system including a navigated initial probe, nested retractors and a navigated final tubular retractor defining an interior passage extending between a proximal end and a distal working end. A multi-planar navigation marker including a plurality of spaced-apart, radiopaque marker bodies can be mounted to the tubular retractor at a predetermined multi-planar spatial and rotational relation to the distal working end. The retractor can optionally include systems for fluid irrigation and suction with differential activation allows for the option of maintaining a dry surgical field or a submerged surgical field depending on the surgeon&#39;s preference during various portions of the procedure. The instrumentation can also include a camera for direct viewing and navigated burrs and/or navigated osteotomes, which allow the surgeon to use direct visualization and/or information from instrument localization on multi-planar images depending on surgeon facility resources.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.16/051,692, filed Aug. 1, 2018, entitled INSTRUMENTATION AND SURGICALMETHOD FOR IMAGE-GUIDED MICROENDOSCOPIC DECOMPRESSION, issuing as U.S.Pat. No. 11,076,920 on Aug. 3, 2021 (Atty. Dkt. No. ASMP60-34046), whichclaims benefit of U.S. Provisional Application No. 62/617,975, filedJan. 16, 2018, entitled INSTRUMENTATION AND SURGICAL METHOD FORIMAGE-GUIDED MICROENDOSCOPIC DECOMPRESSION (Atty. Dkt. No.ASMP60-33993). The aforementioned applications, publications and/orpatents are incorporated by reference herein in their entireties.

TECHNICAL FIELD

The present disclosure relates generally to methods and instrumentationfor microendoscopic surgery and, more specifically, to a method andinstrumentation for performing microendoscopic decompression of thespinal anatomy.

BACKGROUND

Compression of the spinal cord and nerves, known as spinal stenosis, isa common problem that results when bone, disc, or ligamentous structuresencroach on the spinal canal and cause pressure on neurologicstructures. FIG. 1 demonstrates the anatomic structures that contributeto neurologic compression. This pressure results in arm or leg pain,numbness, and/or weakness. The removal of these structures that encroachon the neurologic structures, known as decompression surgery, is one ofthe most common procedures performed in spinal surgery. FIG. 2 depictsthe bony and ligamentous structures removed during a decompressionsurgery. In order to gain access to these structures, surgeonstraditionally make incisions and must move or dissect structures,including muscles and ligaments, in order to perform decompressionsurgery. This results in permanent changes to these muscles andligaments and can result in destabilization of the spinal segments,causing functional limitations, mechanical pain, and possibly leading tofurther surgery.

More recently surgeons have utilized small tubular retractors, which canbe placed between and through muscle fibers, allowing access to thespinal canal with less muscle and ligament disruption. Surgeons havetraditionally used a microscope to view the spinal canal through thetube, but this provides limited visibility and a field of view, which islimited to the area of the tube.

The problem of limited field of view has been in part improved upon byutilizing a small camera placed into the tube, which can be moved todifferent positions, thus allowing improved visualization and increasedfield of view, outside the area of the tube, known as microendoscopicspine surgery. Microendoscopic surgery is very much akin to arthroscopicsurgery of the knees and shoulders, which has gained rapidly inutilization since its inception, as it similarly allows for themanipulation of tissues deep inside the body while minimizing thedetriment to the surrounding structures. As was similarly the case inarthroscopic surgery decades ago, microendoscopic spine surgery islimited at this early stage in development by the lack of tools andtechniques to effectively and safely achieve decompression of theneurologic structures through a smaller working portal with less directvisualization.

One of the unique challenges to spinal anatomy, as compared to that of ashoulder or knee, is the reduced ability to differentiate regionalanatomy. In traditional open spinal surgery, the surgeon can directlyvisualize the facet joints and pars, which define the borders of thespinal canal, and must be preserved during the decompression surgery inorder to maintain the stability of the spinal segment. Visualizing thesestructures requires further tissue dissection, which defeats the purposeof less invasive surgery, and is less feasible when viewing themindirectly, with a camera, in the absence of clear regional identifiableanatomy.

The advent of intraoperative three dimensional or multi-planar (CT orMM) imaging and navigation techniques have provided surgeons the abilityto view real time multi-planar images in the operating room, andfurther, the ability to track and view the location of instrumentsrelative to anatomic structures on multi-planar views.

Navigated microendoscopic spine surgery represents the incorporation ofthese two technologies. While microendoscopic surgery allows forminimally invasive and minimally disruptive access to the spinal canal,and the use of a camera increases the field of view significantly overdirect visualization externally with a microscope, it creates thechallenge of the inability to define regional anatomy, which can beresolved by coupling navigation technology to microendoscopicinstrumentation and techniques. The current systems have limitations dueto retractor design and are based in a dry environment with intermittentirrigation and suction managed by the operator.

The limitations of the retractor, instruments, and technique will beresolved with this novel system.

SUMMARY

The proposed invention is a novel concept, system, and technique formulti-planar (CT or MM) image-guided microendoscopic spinal surgery.

In one aspect, instrumentation for microendoscopic surgery comprises aretractor having a tubular wall defining an interior passage extendingbetween a proximal end and a distal end. The tubular wall of theretractor including a fluid irrigation system having a plurality ofirrigation outlet holes disposed circumferentially around the interiorpassage adjacent the distal end, an irrigation inlet positioned adjacentthe proximal end and at least one irrigation channel fluidly connectingthe irrigation inlet to the plurality of irrigation outlet holes. Acamera including an imaging lens is disposed within the interior passageof the retractor proximal to the irrigation holes. The imaging lensprovides a field of view extending in a distal direction past the distalend of the retractor. A removable multi-planar navigation marker ismounted to the retractor in a first predetermined multi-planar spatialrelation to the distal end of the retractor.

In one embodiment, a portion of the tubular wall of the retractorexcluding only the distal end is substantially radiolucent.

In another embodiment, the distal end of the tubular wall of theretractor is substantially radiopaque.

In a further embodiment, the tubular wall of the retractor furthercomprises a fluid suction system having a plurality of suction inletholes disposed circumferentially around the interior passage at aposition proximal to the camera imaging lens, a suction outlet disposedadjacent the proximal end and at least one suction channel fluidlyconnecting the suction outlet to the plurality of suction inlet holes.

In yet another embodiment, the instrumentation further comprises adilator having a body with a distal dilator tip and multi-planarnavigation marker mounted to the dilator in a second predeterminedmulti-planar spatial relation to the distal dilator tip.

In yet another embodiment, the instrumentation further comprises anavigated microendoscopic burr having a cutting head, the burr beingconfigured to be inserted through the interior passage of the retractoruntil the cutting head is disposed distally beyond the distal end of thetubular wall. When the cutting head is disposed distally beyond thedistal end of the tubular wall, the cutting head is within the field ofview of the imaging lens of the camera.

In a further embodiment, the instrumentation further comprises anavigated osteotome having a cutting blade, the osteotome beingconfigured to be inserted through the interior passage of the retractoruntil the blade is disposed distally beyond the distal end of thetubular wall. When the blade is disposed distally beyond the distal endof the tubular wall, the blade is within the field of view of theimaging lens of the camera.

In another aspect, a surgical method of microendoscopic decompression ona patient, comprises creating a skin opening in a patient and placing aretractor through the skin opening and into proximity to a spinolaminarjunction using multiplanar imaging. The retractor includes a tubularwall defining an interior passage extending between a proximal end and adistal end. The tubular wall of the retractor includes a fluidirrigation system having a plurality of irrigation outlet holes disposedcircumferentially around the interior passage adjacent the distal end,an irrigation inlet positioned adjacent the proximal end and at leastone irrigation channel fluidly connecting the irrigation inlet to theplurality of irrigation outlet holes. A camera including an imaging lensis disposed within the interior passage of the retractor proximal to theirrigation holes. The imaging lens provides a field of view extending ina distal direction past the distal end of the retractor. A removablemulti-planar navigation marker is mounted to the retractor in a firstpredetermined multi-planar spatial relation to the distal end of theretractor. Surgical instruments are inserted through the interiorpassage of the retractor past the distal end of the retractor and intothe field of view of the camera. Positions of the surgical instrumentsare observed in the field of view using the camera, and can be monitoredand navigated on multi-planar imaging. The surgical field can beirrigated via the irrigation system in the retractor and differentiallycontrolled in combination with suction to create either a dry or fluidsubmerged surgical field.

In yet another aspect, instrumentation for microendoscopic surgerycomprises a first retractor having a tubular wall including an innersurface and an outer surface, the interior surface defining an interiorpassage extending between a proximal end and a distal working end. Amulti-planar navigation marker is mounted to the outer surface of thetubular wall, the multi-planar navigation marker including a pluralityof spaced-apart, radiopaque marker bodies. The multi-planar navigationmarker is disposed at predetermined multi-planar spatial and rotationalrelation to the distal working end of the retractor.

In one embodiment, the tubular wall of the first retractor furthercomprises a fluid irrigation system including at least one irrigationoutlet hole formed on the inner surface of the tubular wall and disposedadjacent to the distal working end, at least one irrigation inlet holeformed on the outer surface of the tubular wall and disposed proximallyrelative to the at least one irrigation inlet hole, and a firstfluid-tight passage connecting between the at least one irrigation inlethole and the at least one irrigation outlet hole for transporting fluidtherebetween.

In another embodiment, the first fluid-tight passage is formed withinthe tubular wall of the first retractor between the inner surface andthe outer surface so as to be undetectable on an inner contour of theinner surface or on an outer contour of the outer surface.

In yet another embodiment, the tubular wall of the first retractorfurther comprises a fluid suction system including at least one suctioninlet hole formed on the inner surface of the tubular wall and disposedproximally relative to the at least one irrigation outlet hole, at leastone suction outlet hole formed on the outer surface of the tubular wall,and a second fluid-tight passage connecting between the at least onesuction inlet hole and the at least one suction outlet hole fortransporting fluid therebetween. The first fluid-tight passage isfluidly isolated from the second fluid-tight passage.

In still another embodiment, the second fluid-tight passage is formedwithin the tubular wall of the first retractor between the inner surfaceand the outer surface so as to be undetectable on an inner contour ofthe inner surface or on an outer contour of the outer surface.

In a further embodiment, the instrumentation further comprises a cameraassembly including an elongated camera body and a lens disposed at adistal end of the camera body. The elongated camera body is configuredto be insertable through the proximal end of the first retractor andpositionable in the passage of the retractor such that the lens isdisposed distal to the at least one suction inlet hole and proximal tothe at least one irrigation outlet hole.

In a yet further embodiment, the instrumentation further comprises asecond tubular retractor having a second tubular wall having an innersurface and an outer surface, the interior surface defining an interiorpassage extending between a proximal end and a distal working end. Thetubular wall of the first retractor has a first diameter, and the secondtubular wall of the second retractor has a second diameter that issmaller than the first diameter.

In a still further embodiment, the second tubular retractor furthercomprises a second multi-planar navigation marker mounted to the outersurface of the second tubular wall, the second multi-planar navigationmarker including a plurality of spaced-apart, radiopaque marker bodies.The second multi-planar navigation marker is disposed at predeterminedmulti-planar spatial and rotational relation to the distal working endof the second retractor.

In another embodiment, the instrumentation further comprises a cameraassembly including a lens and an outer housing sheath surrounding thedistal end of the lens, thereby forming an annular space between theouter housing sheath and the camera lens. The outer housing sheath isconfigured to be insertable through the proximal end of at least one ofthe first and second tubular retractors and extend towards the distalworking end of the respective retractor. The annular space is fluidlyconnectable to a suction source such that, when the annular space isconnected to the suction source, any fluid is drawn off the lens intothe annular space.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding, reference is now made to thefollowing description taken in conjunction with the accompanyingDrawings in which:

FIG. 1 is a cross-sectional representation of a portion of the lumbarspine illustrating the relevant anatomic structures associated withcompression of the neural elements;

FIG. 2 is a cross-sectional view of the lumbar spine portion from FIG. 1illustrating an exemplary decompression plan designating areas of boneand ligament that need to be removed in order to decompress the neuralelements;

FIG. 3 is a schematic view of an exemplary initial dilator assembly inaccordance with one aspect positioned adjacent to the lumbar spineportion of FIG. 1, the initial dilator assembly including a probedilator and a detachable marker holder for multi-planar image guidance;

FIGS. 4a-4c show additional details of the initial dilator assembly ofFIG. 3, wherein FIG. 4a is an exploded side view, FIG. 4b is across-sectional end view of the initial dilator taken through line 4 b-4b of FIG. 4a , and FIG. 4c is a cross-sectional end view of the probenavigational marker taken through line 4 c-4 c of FIG. 4 a;

FIG. 5 is a partial cross sectional view of an exemplary retractorsystem in accordance with another aspect positioned adjacent to thelumbar spine portion of FIG. 1, the retractor system includingsequential dilators placed over the initial probe of FIG. 3 and a finalretractor with detachable marker holder for multi-planar image guidance,wherein the final retractor includes an attached housing for thenavigation marker, which has a keyhole configuration for directional fitof the navigation marker.

FIGS. 6a and 6b show additional details of the retractor system of FIG.5, wherein FIG. 6a is a side view of the final retractor and navigationmarker, and FIG. 6b is an end view of the final retractor, sequentialdilators and initial probe showing the nested of these elements;

FIG. 7 is a schematic view of an exemplary retractor in accordance withanother aspect positioned adjacent to the lumbar spinal portion of FIG.1 showing the retractor attached to a table-mounted arm;

FIG. 8 is an anteroposterior (AP) perspective view of a tubularretractor with radiopaque distal retractor tip in accordance with yetanother aspect positioned over a vertebral interspace;

FIG. 9 is a schematic view of an exemplary retractor with beveled distalend in accordance with still another aspect positioned adjacent to aspinolaminar junction, wherein the bevel shortens the medial side of theretractor and allows for the distal retractor end to be placed nearerthe midline;

FIG. 10 is a schematic view of an exemplary tubular retractor systemwith irrigation system and camera in accordance with another aspectpositioned near the lumbar spine portion of FIG. 1, wherein theirrigation holes are disposed distal to the camera lens so as not tohave fluid obscure the view from the camera;

FIG. 11 is a partial perspective view of the distal working end of thetubular retractor of FIG. 10 showing the irrigation outlet holespositioned circumferentially around the inner wall and distally beyondthe camera and light source so that fluid does not obscure the cameralens;

FIG. 12 is a side view of an exemplary tubular retractor system withirrigation system, suction system, camera and navigation marker inaccordance with yet another aspect;

FIG. 13 is a schematic perspective view of the retractor of FIG. 12showing the internal channels for suction and irrigation within the wallof the tubular retractor;

FIG. 14 is a schematic diagram of the retractor system of FIG. 12positioned in a submerged surgical field adjacent to the lumbar spineportion of FIG. 1, wherein the fluid level within the retractor isproximal to the camera lens and slightly proximal to the level of thesuction holes;

FIG. 15 is an enlarged partial perspective view of the distal end of anexemplary camera assembly with suction in accordance with anotheraspect;

FIG. 16 is a schematic view of an exemplary multiple retractor systemincluding a first tubular retractor and a second tubular retractor inaccordance with another aspect positioned near the lumbar spine portionof FIG. 1, wherein the first tubular retractor has optional irrigationand/or suction systems, first camera and optional supplementalstandalone suction tip and wherein the second tubular retractor has areduced-diameter tubular body and second camera, and wherein the secondtubular retractor is positioned on the contralateral side of the spineto allow for visualization of the lateral recess area on the side of thelarger working channel retractor;

FIGS. 17 and 18 are schematic views of an exemplary retractor systemincluding a navigated burr in accordance with another aspect positionednear the lumbar spine portion of FIG. 1, wherein FIG. 17 shows the burrin a first position allowing the working end of the burr to be directedtoward the operator and more effectively remove bone on the sideipsilateral to the working tubular retractor, and FIG. 18 shows the burrin a second position allowing the working end of the burr to be directedaway from the operator and more effectively remove bone on the sidecontralateral to the working tubular retractor;

FIG. 19 is a schematic view of the retractor system of FIG. 17 furtherincluding a second retractor with camera placed on the contralateralside, allowing the surgeon to directly view the ipsilateral recess whileutilizing the primary larger retractor as a working channel forinstruments (i.e., a navigated burr is directed toward the operatorthrough the working channel, performing the ipsilateral laminotomy,while under direct visualization from the contralaterally placedcamera); and

FIGS. 20 and 21 are schematic views of an exemplary retractor systemincluding a navigated angled osteotome in accordance with yet anotheraspect positioned near the lumbar spine portion of FIG. 1, wherein FIG.20 shows the osteotome in a first position allowing the angled workingend of the osteotome to be directed toward the lateral recessipsilateral to the operator, and FIG. 21 shows the osteotomerepositioned so the angled working end is directed toward the lateralrecess contralateral to the operator.

DETAILED DESCRIPTION

Referring now to the drawings, wherein like reference numbers are usedherein to designate like elements throughout, the various views andembodiments of instrumentation and surgical method for image-guidedmicroendoscopic decompression are illustrated and described, and otherpossible embodiments are described. The figures are not necessarilydrawn to scale, and in some instances the drawings have been exaggeratedand/or simplified in places for illustrative purposes only. One ofordinary skill in the art will appreciate the many possible applicationsand variations based on the following examples of possible embodiments.

Referring now to FIGS. 1 and 2, an exemplary cross-section of a lumbarspine region 100 is shown to illustrate the anatomic structuresassociated with spinal stenosis. A dural sac 102 holding neural elements104 of the spinal cord and nerves is disposed in a spinal canal 105formed between a ligamentum flavum 106 and a disc 108. The ligamentumflavum 106 is flanked by superior articular process 110, interiorarticular process 112 and spinous process 114. Neurological compressionoccurs when any of these bone, disc, or liagamentous structures encroachon the spine canal 105 and put pressure on the dural sac 102 and neuralelements 104 therewithin. In many cases, a bulging or rupturing of thedisc 108 presses the dural sac 102 against the ligamentum flavum 106,which is rigidly supported by the adjacent articular processes 110 and112. Decompression surgery involves the removal of selected anatomicalstructures to locally enlarge the spinal canal 105 and relieve thepressure on the dural sac 102 and neural elements 104.

FIG. 2 represents one example of a surgical decompression plan for thelumbar spine region 100 of FIG. 1. Portions of the anatomical structure(denoted with section lines in FIG. 2) can be removed to increase thearea of the spinal canal 105 and relieve pressure on the dural sac 102and neural elements 104. The structures to be removed duringdecompression can be referred to as “target structures.” In the exampleshown, the target structures to be removed include the entire ligamentumflavum 106′ and proximal ends 110′ and 112′ of the respective superiorarticular process 110 and interior articular process 112. It will beunderstood that the removal of the target structures typically occursalong a vertically localized section of the spine to increase the sizeof the spinal canal 105 vertically proximal to the stenosis. It willalso be understood that the anatomical structures and surgical planshown in FIGS. 1 and 2 are exemplary only, and use of the methods andapparatus disclosed herein is not limited thereto, but can be applied toother anatomical structures and surgical plans.

1) Localization and Retractor Placement

To perform a decompression surgery such as that depicted in the plan ofFIG. 2, the surgeon must gain access the target structures, for exampleligamentum flavum 106′ and the target portions 110′ and 112′ of therespective articular processes. Appropriate placement and positioning ofthe tubular retractor system is imperative for optimizing access to thespinal canal 105 and thus allowing the operator to effectively performdecompression surgery. Both the position and vector of the tubularsystem are vital. Plain radiography is traditionally utilized forpositioning of the tubular retractor, which has limited ability todefine these spatial relationships.

Referring now to FIGS. 3, 4 a-c, 5 and 6 a-b, there is illustrated anovel retractor system 300 including an initial dilator assembly andseries of successively larger nested dilators. The retractor system 300is used to accurately position a final retractor 500, through which thesurgical instruments can be inserted to perform the decompression.Markers are attached to the initial dilator and final retractor to allowthree-dimensional positional tracking via radio imaging (e.g.,radiography or fluoroscopy). Navigation is important for positioning theinitial dilator and to confirm the position of the final retractor.

Referring first to FIG. 3, an initial dilator assembly 302 isillustrated in the context of the anatomical structures of the lumbarspine region 100. The initial dilator assembly 302 includes an initialdilator 304, also called a probe, connected to a probe navigation marker306. The probe 304 has an elongated body 307 extending between aproximal end 308 and a distal tip 310. The body 307 of the probe 304typically has a cylindrical cross section of a first diameter anddefines a probe vector 312 extending therebetween directed towards thedistal tip 310. The probe navigation marker 306 is connected to theproximal end 308 of the probe 304 and includes multiple marker bodies314 disposed at predetermined positions relative to the distal tip 310.The marker bodies 314 are typically formed of materials visible viaradio imaging, thus, the marker bodies allow both the location of thedistal tip 310 and orientation of the probe vector 312 to be determinedand/or tracked via radio imaging.

As the procedure begins, the probe 304 is inserted thorough an incisionuntil the distal tip 310 is adjacent to the target structure and thevector 312 of the probe is oriented as desired by the operator. At thispoint, the position and orientation of the marker bodies 314 on theprobe navigation marker 306 can be imaged to provide a record for laterpositioning of the final retractor 500. A plurality of nested dilators316, for example, n nested dilators 316(1), 316(2) . . . 316(n), aresubsequently inserted through the incision over the initial probe 304 intelescoping fashion, each successive nested dilator having asuccessively larger diameter than the previous nested dilator. Tofacilitate placement of the successive nested dilators 316 over theprobe 304 without removal from the incision, the probe navigation marker306 can be removably connected to the proximal end 308 of the probe, forexample by a detachable collar 318. Thus, after positioning the probe304 and imaging the marker bodies 314 of the navigation marker 306, theprobe navigation marker including the collar 318 is removed, allowingfor the successive nested dilators 316(1) . . . 316(n) to be placed overthe probe and into the incision.

Referring now also to FIGS. 4a-c , the probe 304 and the probenavigation marker 306 can be respectively configured such that the probeconnects to the probe navigation marker in a reproducible andpredictable position, i.e., such that the marker bodies 314 of the probenavigation marker are disposed at a known and constant position,including both spatial and angular positions, relative to the probe tip310. In the embodiment illustrated in FIG. 4a-c , the proximal end 308of the probe 304 is configured with a slot 320, and the collar 318 ofthe navigation marker 306 is configured with a matching socket 322having a key 324. The socket 322 can be dimensioned to accept theproximal end 308 of the probe 304 to a predetermined depth, but onlywhen the marker 306 is rotated to orient the key 324 to a predeterminedorientation such that the key fits within the slot 320. In this manner,the probe 304 connects to the probe navigation marker 306 in a totallyreproducible and predictable position in terms of both spatial positionand angular position. The complimentary slot 320 and key 324 of theembodiment illustrated in FIGS. 4a, 4b and 4c is only one example ofconfiguring the probe 304 and the probe navigation marker 306 forpredictable spatial and angular interconnection, and should not beconsidered limiting. In other embodiments, the probe 304 and the probenavigation marker 306 can be configured, respectively, with any set ofcomplementary structures suitable for interconnection in only a singlepredetermined spatial and angular orientation relative to one another.

Referring now to FIG. 5, there are illustrated the retractor system 300and the final retractor 500 positioned proximate to the targetstructures in the lumbar spine region 100. For purposes of illustration,portions of the plurality of nested dilators 316 and the final retractor500 are shown broken away in FIG. 5 to more clearly show the nestedconfiguration. In FIG. 5, the probe navigation marker 306 has alreadybeen removed from the proximal end 308 of the probe 304, and fivesuccessively nested dilators 316, namely 316(1), 316(2), 316(3), 316(4),and 316(5), have been placed over the probe in telescoping fashion. Inother embodiments, a different number of successively nested dilatorscan be used.

Referring now also to FIGS. 6a and 6b , the final retractor 500 includesa tubular body 502 defining an interior passage 507 extending between aproximal end 508 and a distal end 510. A marker mount 504 is attached tothe tubular body 502 at a predetermined spatial and angular positionfrom the distal end 510. A table arm mount 505 is also attached to thetubular body 502. In the illustrated embodiment, the table arm mount 505is attached to the marker mount 504, but this is not required. Once thetubular body 502 of the final retractor 500 is placed over the largestnested dilator (i.e., dilator 316(5) in the illustrated embodiment), aretractor navigation marker 506 can be attached to the marker mount 504.The retractor navigation marker 506 includes multiple marker bodies 514disposed at predetermined positions relative to the marker mount 504,and thus also relative to the distal end 510 of the final retractor 500.The marker bodies 514 are typically formed of materials visible viaradio imaging, thus the marker bodies allow both the location of thedistal tip 510 and angular orientation of the passage 507 to determinedand/or tracked via radio imaging.

The retractor navigation marker 506 allows for placement and angulationof the final retractor 500 before fixing the arm connector 505 to atable-mounted arm 702 (FIG. 7), after which the spatial and angularposition of the final retractor will be maintained during subsequentprocedures. The imaged spatial and angular position of the retractornavigation marker 506 can also be compared to the previously recordedspatial and angular position of the probe navigation marker 306 tothereby determine placement/orientation of the distal end 510 of thefinal retractor 500 compared to the original placement/orientation ofthe distal end 310 of the probe 304. In the illustrated embodiment, theretractor navigation marker 506 is similar, but not identical to theprobe navigation maker 306. In other embodiments, the same navigationmarker can be used for the retractor navigation marker 506 and the probenavigation maker 306. As long as the spatial and angular positions ofthe respective navigation markers 306 and 506 are known relative to therespective distal probe tip/distal retractor end 310 and 510, thepositions of the distal probe tip relative to the distal retractor endcan be determined from imaging, e.g., radio imaging, of the respectivenavigation markers.

Referring now specifically to FIGS. 6a and 6b , there are providedadditional views of the retractor system 300 and the final retractor500. FIG. 6a is a side view of the final retractor 500, showing thetubular body 502, marker mount 504, table arm connector 505, andretractor navigation marker 506. FIG. 6b is a cross-sectional end viewshowing final retractor 500 and portions of the retractor system 300including the probe 304 and nested dilators 316(1) . . . 316(5). It willbe appreciated that the only portion of the retractor navigation marker506 visible in the cross section of FIG. 6b is the portion within thesocket 522.

The marker mount 504 and the retractor navigation marker 506 can berespectively configured such that the marker mount connects to theretractor navigation marker in a reproducible and predictable position,i.e., such that the marker bodies 514 of the retractor navigation markerare disposed at a known and constant position, including both spatialand angular positions, relative to the distal end 510 of the tubularbody 502. In the embodiment illustrated in FIGS. 6a and 6b , theretractor navigation marker 506 is configured with a slot 520 and themarker mount 504 is configured with a matching socket 522 having a key524. The socket 522 can be dimensioned to accept an end of theretraction navigation marker 506 to a predetermined depth, but only whenthe retraction navigation marker is rotated to orient the slot 520 to apredetermined orientation such that the key 524 fits within the slot. Inthis manner, the marker mount 505 connects to the retractor navigationmarker 506 in a totally reproducible and predictable position in termsof both spatial position and angular position. The complimentary slot520 and key 524 of the embodiment illustrated in FIGS. 6a and 6b is onlyone example of configuring the marker mount 505 and the retractornavigation marker 506 for predictable spatial and angularinterconnection, and should not be considered limiting. In otherembodiments, the marker mount 505 and the retractor navigation marker506 can be configured, respectively, with any set of complementarystructures suitable for interconnection in only a single predeterminedspatial and angular orientation relative to one another.

Referring now to FIG. 7, the final retractor 500 is illustrated inposition adjacent to the target structures in the lumbar spinal region100. For purposes of clarity, the dural sac 102 is not illustrated inFIG. 7. The probe 304 and the plurality of dilators 316 comprising theretractor system 300 have been removed from the passage 507 of the finalretractor 500 to provide a clear access path to the target structuresvia the retractor passage. After imaging the retractor navigation marker506 to verify the spatial position of the distal end 510 and the angularorientation of tubular body 502 (and hence the interior passage 507)according to the surgical plan, the final retractor 500 can be rigidlylocked in position, e.g., by connection of the table arm mount 505 to atable arm 702.

Referring now to FIG. 8, there is illustrated another exemplaryembodiment of a final retractor docked against the anatomical structuresof the lumbar spinal region 100. The final retractor 800 is similar inmost respects to the final retractor 500 previously described, thusidentical reference numbers are used for identical features. The finalretractor 800 of this embodiment includes the retractor navigationmarker 506 and attachment structures 504 and 505; however, these are notshown in FIG. 8 for purposes of clarity. During spinal decompressionprocedures, the positioning and localization of the final retractor areof utmost importance. While a navigated system can be used to providemulti-planar localization, some surgeons may rely on intraoperativefluoroscopy, either because of individual preference, real-timefeedback, or the lack of resources for navigation. For this reason, thefinal retractor 800 is adapted for positioning under intraoperativefluoroscopy. The surgeon can utilize anteroposterior (AP) and lateralfluoroscopic views in order to position the final retractor 800. Theposition of the distal end 510 of the tubular body 502 docked againstthe spine is the central point of interest. Surgeons may also beinterested in visualizing metallic (e.g., steel) instruments placedthrough the passage 507 of the tubular body 502 during certain steps ofthe procedure. In preferred embodiments, the final retractor 800 isradiolucent through the majority of the tubular body 502 from theproximal end 508 (which is positioned outside the body), but have aradiopaque marker 802 outlining the working perimeter at the distal end510 of the tubular passage 507 positioned next to the spine. FIG. 8depicts the AP radiographic view of the final retractor 800 withradiopaque distal retractor tip 802 positioned over the vertebralinterspace. This would allow the operator to see exactly where theborders of the distal working end 510 of the retractor 800 arepositioned on plain radiography.

Referring now to FIG. 9, there is illustrated yet another exemplaryembodiment of a final retractor positioned near the anatomicalstructures of a spinolaminar junction 130. The final retractor 900 issimilar in most respects to the final retractor 500 previouslydescribed, thus identical reference numbers are used for identicalfeatures. The final retractor 900 of this embodiment includes theretractor navigation marker 506 and attachment structures 504 and 505;however, these are not shown in FIG. 9 for purposes of clarity. Whereasthe tubular body 502 of final retractor 500 has a distal end 510 that isoriented substantially perpendicular to the longitudinal passage 507,the tubular body 902 of the final retractor 900 is configured to form abevel 904 at the distal end 910 in order to facilitate the docking ofthe distal end of the retractor on the curved structures 132 of thespinolaminar junction 130, as illustrated in FIG. 9. When the surgicalprocedure involves a bilateral decompression through a unilateralparaspinal approach, the positioning of the final retractor 900 nearestto the spinolaminar junction 130 facilitates the decompression of thecontralateral spinal canal. One limitation of the previously describedfull (i.e., perpendicular distal end) tubular retractor 500 is that thespinolaminar junction 130 needs to be undercut in order for the tubebody to be repositioned near the midline. The bevel 904 on the retractor900 shortens the medial side of the retractor, and thus allows for thedistal retractor end 910 to be placed near the midline and also allowsfor improved unimpaired visualization (denoted by dashed lines 912 inFIG. 9) of the contralateral spinal canal, e.g., by a camera 914disposed in passage 507 of the retractor.

2) Microendoscopic Tube System with Irrigation and Suction

Once the tubular final retractor, e.g., retractor 500, 800 or 900 isplaced and appropriately positioned, the operator can begin with thedecompression. The first step is to perform the laminotomy, in which aportion of the bony elements 110, 112 and/or 114 are removed to allowaccess to the ligamentum flavum 106. The ligamentum flavum 106, and itsmidline raphe, serve as a relatively consistent anatomic landmark todemonstrate the midline. Exposure of these structures and bony removalis facilitated in some portion by a burr. The burr typically generatesbony debris, which requires continual irrigation and suction in order toremove debris and allow continued visualization. Irrigation istraditionally performed by the operator using a syringe, and suction issimilarly performed by manual control of a suction tip.

Referring now to FIGS. 10 and 11, there is illustrated another exemplaryretractor system in accordance with another aspect of the disclosure. Inparticular, a retractor system 1000 is illustrated having irrigationfeatures incorporated into the final retractor 1001 in order to free theoperator's hands for instrumentation. Although not illustrated in FIGS.10 and 11, the retractor system 1000 can include the previouslydescribed retractor system 300 and retractor navigation marker 506 (bothshown in, e.g., FIG. 5) for insertion, placement, orientation andimaging of the final retractor 1001. In addition, the final retractor1001 is similar in many respects to the final retractors 500, 800 and900 previously described, thus identical reference numbers are used foridentical features.

In the retractor system 1000, the tubular final retractor 1001 includesan internal irrigation system 1002 to guide a flow of an irrigationfluid (e.g., water, saline, etc.) through a fluid distribution structureof the retractor to one or more outlet holes 1004 located near theretractor's distal working end 510. In some embodiments, the fluiddistribution structure of the retractor 1001 includes one or more fluidchannels formed within the tubular wall 502 (i.e., between the inner andouter wall surfaces) such that the presence of the channels does notchange the overall wall thickness compared to portions of the wallwithout the channels. In other embodiments, the fluid distributionstructure of the retractor 1001 includes one or more discrete tubes orfluid channels routed along the exterior of the tubular wall 502. Instill other embodiments, the fluid distribution structure of theretractor 1001 includes one or more discrete tubes or fluid channelsrouted along the interior wall 509 of the retractor, in which case thesuccessively nested retractors 316 can be configured to allow clearancefor such tubes/channels.

FIG. 10 shows the relative position of the camera 914, irrigation holes1004, and a handheld suction device 1006 using phantom lines to show theelements within the passage 507. The manual controlled suction tip 1006may be required in the working field if the retractor 1001 itself doesnot incorporate a suction system, or if the suction incorporated intothe retractor is not able to collect fluid in the working field. In theillustrated embodiment, a plurality of circumferentially placed outletholes 1004 are disposed along the internal wall 509 of the retractor1001 near the distal end 510 to facilitate irrigation over the entirefield of view through the internal passage 507. In the illustratedembodiment, the irrigation holes 1004 are disposed distal to the finalposition of the camera lens 916 such that fluid will not contact thecamera lens and obscure the view during normal use. FIG. 11 provides anenlarged view of the distal end 510 of the final retractor 1001 toillustrate the relative position of the camera 914, light source 918,and irrigation outlet holes 1004. In some embodiments, water flow to theoutlet holes 1004 can be controlled by a foot pedal in order to free theoperator's hands for instruments and suction.

Referring now to FIGS. 12 and 13, there is illustrated another exemplaryretractor system in accordance with another aspect of the disclosure. Inparticular, a retractor system 1200 includes fluid suction features inaddition to fluid irrigation features incorporated into the finalretractor 1201 in order to further free the operator's hands forinstrumentation. Although not illustrated in FIGS. 12 and 13, theretractor system 1200 can comprise the previously described retractorsystem 300 for insertion, placement, orientation and/or imaging of thefinal retractor 1201. The final retractor 1201 is similar in manyrespects to the final retractors 500, 800, 900 and 1001 previouslydescribed, thus identical reference numbers are used for identicalfeatures.

The final retractor 1201 includes fluid suction features in the tubularretractor body 502. Due to the fact that the working area is beyond thedistal end 510 of the tubular retractor 1201, fluid in the surgical bedmust typically be removed with a separate hand-held suction device(e.g., suction wand 1006 of FIG. 10). The ability to submerge theworking area of the surgical field entirely under water can provide abenefit in many situations. For instance, bone debris created when usingthe burr would be immediately swept away from the working field,improving visualization. Further, fluid would travel between tissueplanes, such as between the ligamentum flavum and dura, makingdissection and removal of tissue safer and less likely to result indural injury.

The final retractor 1201 includes one or more suction (i.e., fluidinlet) holes 1204 and one or more irrigation (i.e., fluid outlet) holes1004 disposed on the interior wall 509 of the tubular retractor body502. In some embodiments, the suction holes 1204 can be disposedproximal to the irrigation holes 1004 along the internal passage 507 ofthe tubular body 502. In other embodiments, the suction holes 1204 canbe disposed proximal to the final position (i.e., furthermost insertionpoint) of the camera lens 916 and the irrigation holes 1004 can bedisposed distal to the final position of the camera lens. In theillustrated exemplary embodiment of FIG. 12, a first plurality ofsuction holes 1204 are disposed circumferentially around the interiorwall 509 of the tubular body 502 at a first position along the passage507 proximal to the final position of the camera lens 916, and a secondplurality of irrigation holes 1004 are disposed circumferentially aroundthe interior wall at a second position distal to the final position ofthe camera lens. The combination of the irrigation and fluid source 1004placed distal to the camera lens 916 and the suction holes 1204 placedproximal to the camera lens will allow the system to create a workingfield and visualization point that are entirely submerged in fluid.

FIG. 12 illustrates the relative location of the irrigation holes 1004and suction holes 1204 on the internal (i.e., interior) surface 509 ofthe retractor 1201 (the holes 1004 and 1204 are shown in broken linebecause they open only on the interior wall of the retractor). Anirrigation fluid inlet connection 1206 and a suction outlet connection1208 can be provided on the exterior surface of the retractor 1201. Theirrigation inlet connection 1206 is in fluid connection with theirrigation outlet holes 1004, and the suction outlet connection 1208 isin fluid connection with the suction inlet holes 1204. The suction andirrigation systems are fluidly isolated from one another. The inletconnection 1206 and the outlet connection 1208 can be disposed on theproximal portion of the retractor 1201 so the connections can remainoutside the patient for attachment to external suction and irrigationsources (not shown). When the irrigation fluid inlet hole 1206 isconnected to a source of the irrigation fluid, the irrigation fluid canflow out from the irrigation outlet holes 1004 and into the adjacentsurgical field and/or fill the tubular passage 507 of the retractor1201. When the suction outlet connection hole 1208 is connected to asource of suction (e.g., vacuum), irrigation fluid at or near thesuction inlet holes 1204 can flow into the suction inlet holes andthereby be removed from the tubular passage 507 of the retractor 1201and/or adjacent surgical field.

Referring now specifically to FIG. 13, there is illustrated an exemplaryconfiguration for the internal suction and irrigation channels (ormanifolds) housed within the tubular retractor body 502 of the retractor1201. The irrigation channels 1210, 1211 connect the irrigation inletconnection 1206 on the outside surface of the tubular body 502 to theirrigation outlet holes 1004 (not shown) on the inside surface 509 ofthe body, and the suction channels 1212, 1213 connect the suction outletconnection 1208 on the outside surface of the body to the suction inletholes 1204 (not shown) on the inside surface of the body. In someembodiments, the irrigation channels 1210, 1211 and/or the suctionchannels 1212, 1213 can be disposed within the wall structure of thetubular body 502 (i.e., between the inner and outer wall surfaces) sothat there is no protrusion of the channels into the interior passage507 or other change of overall wall thickness due to the channels;however, in other embodiments, one or more of the channels may bedisposed on the inner or outer surface of the tubular body. In theexemplary embodiment of FIG. 13, the channels for suction 1212, 1213 andfor irrigation 1210, 1211 are configured so that there is notoverlapping or crossing of the respective channels, such that thicknessof the tubular retractor needed to house the respective manifolds can beminimized. As previously described, the inlet connection 1206 and outletconnection 1208 can be disposed on a proximal portion of the retractor1201 so they can remain outside the patient for attachment to externalsuction and irrigation sources.

Referring now to FIG. 14, when both the distal irrigation system (e.g.,1004, 1206, 1210 and 1211) and proximal suction system (e.g., 1204,1208, 1212 and 1213) are active, the irrigation fluid 1402 can flow fromthe distal end 510 of the retractor 1201, fill the surgical bed 1404,and fill the distal working end of the tubular retractor body 502 to alevel (denoted 1406) proximal to the camera lens 916, until it nears theproximal end 508 of the retractor where the suction holes 1204 willremove excess fluid and any generated debris. FIG. 14 demonstrates theretractor 1201 in place with a submerged surgical field and water levelabove the camera lens 916 to the level of the suction holes 1204. Thesuction holes 1204 can prevent fluid 1402 from rising beyond theproximal end 508 of the tube body 502 and out of the patient andsurgical field 1404, thereby maintaining a dry environment outside thetubular retractor. The distal fluid irrigation source 1004 and proximalsuction holes 1204 can also serve to remove debris by drawing it out ofthe surgical bed 1404, beyond the camera lens 916, and to the proximalsuction tubes 1212 and 1213 for removal from the surgical field, thusmaintaining a clear fluid working environment to facilitate improvedvisualization.

This combination of features will provide the option of either a dry orfluid submerged working environment. If the procedure calls forimplantation of instrumentation (such as a fusion device), bone graftmaterial, or other biologic material, a dry environment may be necessaryto place and maintain material in its intended position. However, otherportions of a procedure which may generate debris, such a burring ofbone during laminotomy, may be better achieved while the surgical fieldis submerged in a fluid environment. Using the disclosed retractors,e.g., retractor 1201, the operator can perform certain portions of theprocedure, such as decompression and laminotomy, in a fluid environmentby continuously activating both the distal irrigation system (e.g.,through irrigation holes 1004) and proximal suction system (e.g.,through suction holes 1204), and then elect to use only intermittentdistal irrigation as needed to maintain a dry environment during theinsertion of implants or biologic material. In order to free theoperator's hands further, the irrigation system and suction system inthe retractor 1201 can be differentially controlled by foot pedals (notshown) so that irrigation and suction can be manually controlledintermittently or both turned on constantly to maintain a fluidsubmerged environment.

Referring now to FIG. 15, there is illustrated an alternative cameraassembly with suction 1500 according to another aspect. During use ofthe retractor 1201 with both irrigation and suction systems, the distalworking end of the scope (i.e., camera 914) with the lens 916 can moveintermittently between a dry environment and a wet environment duringthe procedure. Camera lenses that go from a fluid to dry environmentoften get fluid residue on the lens 916 that can obscure the view. Tominimize this problem, in some embodiments the camera assembly withsuction 1500 can include an outer housing sheath 1502 that surrounds atleast the distal end of the camera 914, thereby forming an annularpassage 1504 around the lens 916. The annular passage 1504 can beconnected to suction to provide a self-cleaning mechanism by constantlyremoving fluid residue from the distal end of the camera scope lens 916.This will allow the operator to continue working uninterrupted whentransitioning from wet to dry environment, rather than having to removethe endoscope and camera continuously for manual cleaning. The cameraassembly with suction 1500 can be used for the camera 916 inserted inthe passage 507 of a final retractor (e.g., retractor 1201), or as astand-alone camera as further described below.

Referring now to FIG. 16, given the limitation of field of view of theipsilateral lateral recess, a retractor system 1600 according to anotheraspect includes a second, smaller-diameter tubular retractor 1602 inaddition to the main retractor 1604. The main retractor 1604 can besimilar to retractors 500, 800, 900, 1001 and/or 1201 previouslydescribed (for purposes of illustration, some details of the retractorare omitted in FIG. 16), and can be equipped with a first camera 914′ orfirst camera with suction assembly 1500′ positioned inside the tubularbody 502′. The second retractor 1602 can also be similar to retractors500, 800, 900, 1001 and/or 1201, except having a smaller diameter forthe tubular body 502″ compared to the tubular body 502′ of the mainretractor 1604. The second retractor 1602 can be positioned on thecontralateral side, which allows placement of a second camera 914″ orsecond camera with suction assembly 1500 inside the tubular body 502″directed toward the contralateral side of the spine. In FIG. 16, therespective fields of view 1606′ and 1606″ of the cameras 914′ and 914″are denoted by broken lines.

3) Navigated Microendoscopic Burr

Referring now to FIGS. 17-19, there is illustrated a surgicalinstrumentation system 1700 including a navigated microendoscopic burr1702, the distal end of which can be inserted through the interiorpassage of a tubular retractor 1704. A burr, e.g., burr 1702, is anessential component for bone removal. Some portions of bone removal,including the removal of a portion of the base of the spinous process114 to allow for positioning of the tubular retractor 1704 more midline,is best achieved with a burr. Similarly, the undercutting of thecontralateral lamina is also best performed with a burr. The burr 1702can include a burr tip 1706 mounted in a tip holder 1708 extending froma handpiece 1710. The burr 1702 can further include a navigation marker1712 connected to a proximal portion of the handpiece 1710. The tubularretractor 1704 can be similar to retractors 500, 800, 900, 1001 and/or1201 previously described (for purposes of illustration, some details ofthe retractor are omitted in FIGS. 17-19). The navigation marker 1712can be similar to navigation markers 306 and 506 previously described,and can include radio-opaque marker bodies 1714 similar to marker bodies314 and 514. The navigation marker 1712 can be either permanentlyattached or removably attachable to the handpiece 1710. In either case,when attached, the marker bodies 1714 are positioned at a predeterminedlocation relative to the burr tip 1706, thus, the marker bodies allowboth the location and orientation of the burr tip 1706 to be determinedand/or tracked via radio imaging.

As previously described, prior to bone removal and identification of themidline ligamentum raphe, there are limited anatomic landmarks that canbe directly visualized to provide information about spatialrelationships. Navigation of the burr 1702 with respect to multi-planarimage reconstructions can allow the operator to identify the location ofthe burr tip 1706 on image reconstructions and thus direct the burr andbone removal in a manner which allows adequate bone removal fordecompression of the neurologic elements, without compromising keystabilizing structures like the facet joint and the pars. This can helpavoid the problem of iatrogenic instability after decompression surgery.

Referring now specifically to FIGS. 17 and 18, to allow the operator tomaintain hold on the handpiece 1710 during use, in some embodiments theburr 1702 has a total working length, from distal end of the tip 1706 tothe proximal end of the tip holder 1708, which is longer then the lengthof the tubular retractor 1704. The tip holder 1708 is preferablyconfigured to be as small as possible with regard to circumference anddiameter in order to minimize the area within the passage 507 of thetubular retractor 1704 it occupies while still maintaining stability ofthe burr tip 1706. Because the burr tip 1706 may need to remove bone onboth the side ipsilateral and contralateral to the retractor 1704, insome embodiments the burr tip holder 1708 extending from the handpiece1710 is configured, in an arc-shaped configuration (as illustrated) oran angled configuration (not shown) such that the burr tip can be placedin a position to work either toward or away from the operator byrotating the handpiece. For example, FIG. 17 illustrates the navigatedburr 1702 rotated into a first position to decompress the ipsilateralside interior articular process 112′, and FIG. 18 illustrates thenavigated burr rotated into a second position to decompress thecontralateral side interior articular process 112″. As previouslydescribed, the tip holder portion 1708 of the burr 1702 has apredetermined configuration such that the tip 1706 will have a knownposition in space relative (in both position and orientation) to thetracking markers 1712 and 1714 attached to the burr, which will allowthe tip 1706 to be accurately depicted on multi-planar imagereconstructions.

Referring now to FIG. 19, in a further embodiment, the surgicalinstrumentation system 1700 can include a second tubular retractor 1716to facilitate direct visualization of the decompression during certainparts of the procedure. The second tubular retractor 1716 can be similarto second retractor 1602, in other words, similar to previous retractors500, 800, 900, 1001, 1201 and/or 1704, except having a smaller diameterfor the tubular body 502″ compared to the tubular body 502′ of the mainretractor, e.g., retractor 1704. In the illustrated embodiment of FIG.19, the surgical instrumentation system 1700 includes the firstretractor 1704 placed in the ipsilateral position for insertion andoperation of the burr 1702, and the second tubular retractor 1716 withcamera 914 placed in the contralateral position and oriented for directvisualization of the decompression on the ipsilateral side of the spine(the field of view for the camera 914 being denoted by dotted lines1718).

4) Navigated Osteotomes

Referring now to FIGS. 20 and 21, there is illustrated a surgicalinstrumentation system 2000 including a navigated osteotome 2002.Osteotomes are sharp flat cutting tools which allow for removal of boneby creating a thin straight cut with the distal end. Osteotomes can beutilized to create initial bony cuts which define the borders of thebony decompression. The navigated osteotome 2002 includes a distalcutting portion 2004 (also called the distal end or working end)connected by an elongated shaft 2008 to a handle/handpiece 2010. Thedistal end 2004 can be inserted through the interior passage 507 of atubular retractor, for example the retractor 1704 or any of the otherretractors disclosed herein, to reach the site of the decompression.

In the context of microendoscopic decompression, where there is limiteddirect visualization, navigating the osteotome on multi-planar imagingand making initial bone cuts in this manner can define the lateralborders of the decompression and provide the operator with anatomicboundaries which can be clearly visualized. To facilitate suchnavigation, the navigated osteotome 2002 can further include anavigation marker 2012 connected to a proximal portion of the handpiece2010. The navigation marker 2012 can be either permanently attached orremovably attachable to the handpiece 2010. In either case, whenattached, the marker bodies 2014 are positioned at a predeterminedlocation relative to the distal portion 2004, thus, the marker bodiesallow both the location and orientation of the sharp distal portion 2004to be determined and/or tracked via radio imaging.

The shape of the osteotome 2002 can be important in defining thefunctional ability to make cuts in a particular desired direction,especially when the operator is working through the limitations of atubular retractor, for example, the retractor 1704. In some cases, theosteotome cuts on the ipsilateral and contralateral sides will requiredifferent angulation of the osteotome 2002 in order to achieve thedesired direction of the cut. Given that the operator is limited in themovement of the shaft 2008 and/or handle 2010 within the passage 507 ofthe tubular retractor 1704, in such cases the working end 2004 of theosteotome will need much variation in the angle of the osteotome bladerelative to the shaft in order to achieve the necessary cut angles.Therefore, in some embodiments the distal working end 2004 of theosteotome 2002 is configured to extend from the shaft 2008 in an angledconfiguration such that the working end can be placed in a position towork either toward or away from the operator by changing the angle ofthe handpiece 2010. In other words, a first line along the center of theworking end 2004 will form a configuration angle, denoted θ, with asecond line along the center of the shaft 2008. In some embodiments, thenavigated osteotome 2002 can have the configuration angle θ from 10degrees to 80 degrees. In other embodiments, the navigated osteotome2002 can have the configuration angle θ from 20 degrees to 60 degrees.In still other embodiments, the navigated osteotome 2002 can have theconfiguration angle θ from 15 degrees to 50 degrees. It will beunderstood that these angles θ are for exemplary osteotomes 2002, andare not limiting.

For example, FIG. 20 illustrates the navigated osteotome 2002 havingconfiguration angle θ of about 45 degrees inserted through the retractor1704 into a first position wherein the working end 2004 is at a firstdepth and a first working angle to decompress the ipsilateral sideinterior articular process 112′. FIG. 21 illustrates the navigatedosteotome 2002 repositioned within the retractor 1704 into a secondposition wherein the working end is at a second depth and a secondworking angle to decompress the contralateral side interior articularprocess 112″. These bone cuts could be made using navigation during theinitial phase of the recess decompression in order to define theboundaries of the decompression. This will allow the operator todirectly visualize the bony boundaries of the decompression.

It will be appreciated by those skilled in the art having the benefit ofthis disclosure that this instrumentation and surgical method forimage-guided microendoscopic decompression provides navigated retractorsystems with optional irrigation and/or suction systems, camera systemswith optional suction systems for use with such retractor systems orstandalone use, and navigated instruments including burrs and osteotomesfor use with such retractor systems or standalone use. It should beunderstood that the drawings and detailed description herein are to beregarded in an illustrative rather than a restrictive manner, and arenot intended to be limiting to the particular forms and examplesdisclosed. On the contrary, included are any further modifications,changes, rearrangements, substitutions, alternatives, design choices,and embodiments apparent to those of ordinary skill in the art, withoutdeparting from the spirit and scope hereof, as defined by the followingclaims. Thus, it is intended that the following claims be interpreted toembrace all such further modifications, changes, rearrangements,substitutions, alternatives, design choices, and embodiments.

What is claimed is:
 1. Instrumentation for surgery comprising: aretractor having a wall with an inner surface and an outer surface, theinner surface defining an interior passage extending through theretractor between a proximal end and a distal end; the wall of theretractor including a fluid irrigation system having an irrigationoutlet hole formed only in the inner surface of the wall and disposedwithin the interior passage near the distal end, an irrigation inletformed in the outer surface of the wall, and at least one irrigationchannel disposed within the wall between the inner surface and the outersurface and fluidly connecting the irrigation inlet to the irrigationoutlet hole; the wall of the retractor further including a fluid suctionsystem having a suction inlet hole formed only in the inner surface ofthe wall and disposed within the interior passage at a position proximalto the irrigation outlet hole, a suction outlet formed in the outersurface of the wall, and at least one suction channel formed between theinner surface and the outer surface of the wall and fluidly connectingthe suction outlet to the suction inlet hole; and a camera including animaging lens disposed within the interior passage of the retractor, theimaging lens providing a field of view extending in a distal directionpast the distal end of the retractor.
 2. The instrumentation accordingto claim 1, wherein the fluid irrigation system and the fluid suctionsystem are fluidly isolated from one another to allow fluid to be addedinto the interior passage of the retractor near the distal end with thefluid irrigation system while concurrently withdrawing fluid from theinterior passage of the retractor proximal to the irrigation outlet holewith the fluid suction system, and the fluid irrigation system and thefluid suction system can be differentially controlled intermittently orboth turned on constantly to selectively create either a fluid submergedsurgical field or a dry surgical field.
 3. The instrumentation accordingto claim 1, wherein a portion of the wall of the retractor excludingonly the distal end is radiolucent.
 4. The instrumentation according toclaim 3, wherein the distal end of the wall of the retractor isradiopaque.
 5. The instrumentation according to claim 1, furthercomprising a multi-planar navigation marker mounted to the retractor ina first predetermined multi-planar spatial relationship to theretractor.
 6. The instrumentation according to claim 5, furthercomprising: a dilator having a body with a distal dilator tip; and adilator multi-planar navigation marker mounted to the dilator in asecond predetermined multi-planar spatial relation to the dilator. 7.The instrumentation according to claim 6, wherein the dilatormulti-planar navigation marker is mounted removably to the dilator. 8.The instrumentation according to claim 1, wherein the distal end of thewall of the retractor is configured with a beveled tip having ashortened medial side configured to facilitate placement against thespinolaminar junction.
 9. The instrumentation according to claim 1,further comprising: a navigated bone removal device having a workingend, the bone removal device being configured to be inserted through theinterior passage of the retractor until the working end is disposeddistally beyond the distal end of the wall of the retractor; and whereinwhen the working end is disposed distally beyond the distal end of thewall of the retractor, the working end is within the field of view ofthe imaging lens of the camera.
 10. The instrumentation according toclaim 1, further comprising: a navigated osteotome having a cuttingblade, the osteotome being configured to be inserted through theinterior passage of the retractor until the blade is disposed distallybeyond the distal end of the wall of the retractor; and wherein when theblade is disposed distally beyond the distal end of the wall of theretractor, the blade is within the field of view of the imaging lens ofthe camera.
 11. Instrumentation for surgery comprising: a firstretractor having a wall including an inner surface and an outer surface,the inner surface defining an interior passage extending between aproximal end and a distal working end, the interior passage configuredto accommodate the intermittent insertion of surgical instrumentstherethrough from the proximal end through the distal working end; andthe wall of the first retractor further comprising a fluid irrigationsystem including: at least one irrigation outlet hole formed only on theinner surface of the wall facing the interior passage; at least oneirrigation inlet hole formed only on the outer surface of the wall andspaced apart from at least one irrigation outlet hole; and a firstfluid-tight passage disposed within the wall of the retractor betweenthe inner surface and the outer surface connecting between the at leastone irrigation inlet hole and the at least one irrigation outlet holefor transporting fluid therebetween; and the at least one irrigationinlet hole being connectable to a source of an irrigation fluid suchthat, when the at least one irrigation inlet hole is connected to thesource of the irrigation fluid, the irrigation fluid flows through thefirst fluid-tight passage and into the interior passage from the atleast one irrigation outlet hole, including during the absence ofsurgical instruments from the interior passage.
 12. The instrumentationaccording to claim 11, wherein the first fluid-tight passage is formedwithin the wall of the first retractor between the inner surface and theouter surface so as to be undetectable on an inner contour of the innersurface or on an outer contour of the outer surface.
 13. Theinstrumentation according to claim 11, wherein the wall of the firstretractor further comprises a fluid suction system including: at leastone suction inlet hole formed only on the inner surface of the wallfacing the interior passage and spaced apart from the at least oneirrigation outlet hole; at least one suction outlet hole formed on theouter surface of the wall; and a second fluid-tight passage disposedwithin the wall of the retractor between the inner surface and the outersurface connecting between the at least one suction inlet hole and theat least one suction outlet hole for transporting fluid therebetween;and wherein the first fluid-tight passage is fluidly isolated from thesecond fluid-tight passage; and the at least one suction outlet holebeing connectable to a source of suction such that, when the at leastone suction outlet hole is connected to the source of suction, theirrigation fluid can flow into the at least one suction inlet hole. 14.The instrumentation according to claim 13, wherein the secondfluid-tight passage is formed within the wall of the first retractorbetween the inner surface and the outer surface so as to be undetectableon an inner contour of the inner surface or on an outer contour of theouter surface.
 15. The instrumentation according to claim 13, furthercomprising: a camera assembly including an elongated camera body and alens disposed at a distal end of the camera body; and wherein theelongated camera body is configured to be insertable through theproximal end of the first retractor.
 16. The instrumentation accordingto claim 11, further comprising: a multi-planar navigation markermounted to the wall, the multi-planar navigation marker including aplurality of spaced-apart, radiopaque marker bodies; and wherein themulti-planar navigation marker is disposed at predetermined multi-planarrelation to the retractor, including during the absence of surgicalinstruments in from the interior passage.
 17. The instrumentationaccording to claim 11, further comprising: a second retractor having asecond wall having an inner surface and an outer surface, the interiorsurface defining an interior passage extending between a proximal endand a distal working end; wherein the wall of the first retractor has afirst diameter; and wherein the second wall of the second retractor hasa second diameter that is smaller than the first diameter.
 18. Theinstrumentation according to claim 17, wherein the second retractorfurther comprises: a second multi-planar navigation marker mounted tothe second wall, the second multi-planar navigation marker including aplurality of spaced-apart, radiopaque marker bodies; and wherein thesecond multi-planar navigation marker is disposed at predeterminedmulti-planar relation to the second retractor.
 19. The instrumentationaccording to claim 11, further comprising: a camera assembly including alens and an outer housing sheath surrounding the distal end of the lens,thereby forming an annular space between the outer housing sheath andthe camera lens; wherein the outer housing sheath is separable from thewall of the first retractor and is configured to be insertable throughthe proximal end of the first retractor and extend towards the distalworking end of the first retractor; wherein the annular space is fluidlyconnectable to a suction source such that, when the annular space isconnected to the suction source, any fluid is drawn off the lens intothe annular space.
 20. Instrumentation for surgery comprising: aretractor having a body defining an exterior surface and an interiorpassage extending through the body between a proximal end and a distalend; the retractor including a fluid irrigation system having anirrigation outlet disposed within the interior passage near the distalend, an irrigation inlet disposed on the exterior surface and spacedapart from the irrigation outlet, and an irrigation channel formedaxially within the body and fluidly connecting the irrigation inlet tothe irrigation outlet; the retractor further including a fluid suctionsystem having a suction inlet disposed within the interior passage at aposition proximal to the irrigation outlet, a suction outlet disposed onthe exterior surface and spaced apart from the suction inlet, and asuction channel formed axially within the body and fluidly connectingthe suction outlet to the suction inlet; wherein the fluid irrigationsystem and the fluid suction system are fluidly isolated from oneanother to allow fluid to flow into the interior passage from the fluidirrigation system while concurrently withdrawing fluid from the interiorpassage with the fluid suction system; and a camera including an imaginglens disposed within the interior passage, the imaging lens providing afield of view extending in a distal direction past the distal end of theretractor.